body {
    margin: 0;/*外边距*/
    padding: 0; /*内边距*/
    display: flex;/*弹性布局*/
    justify-content: center;/*元素位于容器的中心。*/
    align-items: center;/*居中对齐弹性盒的各项 <div> 元素*/
    min-height: 100vh;/*最小高度*/
    background: #89179e;/*背景颜色*/
}

.loader {
    position: relative;/*relative:相对定位 fixed:相对于浏览器窗口是固定位置 absolute :绝对定位：相对于最近的已定位父元素*/
    width: 300px;/*宽*/
    height: 300px;/*高*/
    transform-style: preserve-3d;/*3D转换*/
    transform: perspective(500px) rotateX(60deg);/*透视视图 沿着 X 轴的 3D 旋转*/
}

.loader span {
    position: absolute;/*absolute :绝对定位：相对于最近的已定位父元素*/
    display: block;/*块级元素*/
    border: 2px solid #fff;/*边框 实心 颜色*/
    box-sizing: border-box;/*以某种方式定义某些元素  指定宽度和高度（最小/最大属性）确定元素边框*/
    border-radius: 50%;/*圆角*/
    transform: translateZ(-100px);/*3D 转换，用 Z 轴的值*/
    animation: animate 3s ease-in-out infinite;/*定义个动画叫animate 动画有一个缓慢的开始和一个缓慢的结束。*/
}

@keyframes animate {
    0%, 100% {/*0-100%   from (和0%相同) to (和100%相同)*/
        transform: translateZ(-100px);
    }
    50% {
        transform: translateZ(100px);
    }
}

.loader span:nth-child(1) {
    top: 0;/*把图像的上边缘设置在其包含元素上边缘之下5像素高的位置*/
    left: 0;
    right: 0;
    bottom: 0;
    animation-delay: 1.3s; /*等待*秒，然后开始动画*/
}

.loader span:nth-child(2) {
    top: 10px;
    left: 10px;
    right: 10px;
    bottom: 10px;
    animation-delay: 1.3s;
}

.loader span:nth-child(3) {
    top: 20px;
    left: 20px;
    right: 20px;
    bottom: 20px;
    animation-delay: 1.2s;
}

.loader span:nth-child(4) {
    top: 30px;
    left: 30px;
    right: 30px;
    bottom: 30px;
    animation-delay: 1.1s;
}

.loader span:nth-child(5) {
    top: 40px;
    left: 40px;
    right: 40px;
    bottom: 40px;
    animation-delay: 1s;
}

.loader span:nth-child(6) {
    top: 50px;
    left: 50px;
    right: 50px;
    bottom: 50px;
    animation-delay: 0.9s;
}

.loader span:nth-child(7) {
    top: 60px;
    left: 60px;
    right: 60px;
    bottom: 60px;
    animation-delay: 0.8s;
}

.loader span:nth-child(8) {
    top: 70px;
    left: 70px;
    right: 70px;
    bottom: 70px;
    animation-delay: 0.7s;
}

.loader span:nth-child(9) {
    top: 80px;
    left: 80px;
    right: 80px;
    bottom: 80px;
    animation-delay: 0.6s;
}

.loader span:nth-child(10) {
    top: 90px;
    left: 90px;
    right: 90px;
    bottom: 90px;
    animation-delay: 0.5s;
}

.loader span:nth-child(11) {
    top: 100px;
    left: 100px;
    right: 100px;
    bottom: 100px;
    animation-delay: 0.4s;
}

.loader span:nth-child(12) {
    top: 110px;
    left: 110px;
    right: 110px;
    bottom: 110px;
    animation-delay: 0.3s;
}

.loader span:nth-child(13) {
    top: 120px;
    left: 120px;
    right: 120px;
    bottom: 120px;
    animation-delay: 0.2s;
}

.loader span:nth-child(14) {
    top: 130px;
    left: 130px;
    right: 130px;
    bottom: 130px;
    animation-delay: 0.1s;
}

.loader span:nth-child(15) {
    top: 140px;
    left: 140px;
    right: 140px;
    bottom: 140px;
    animation-delay: 0s;
}

